Its prose is so opaque, normal people will need a can opener to get into it, but here’s the CliffsNotes: “We didn’t do anything wrong, but even if we did, it wasn’t nice to rat us out to the DA.”

As if facts matter in the shark tank of New York politics.

New Yorkers got their first clue that de Blasio actually belongs in the kiddie pool just six weeks into his administration, when he personally arranged a middle-of-the-night release for Orlando Findlayter, a storefront bishop from Brooklyn who had been arrested on warrant violations.

No big deal, really, but such things are supposed to be done without fingerprints — yet de Blasio wrote his name on this one with a red neon Sharpie.

Why he thought he could get away with sticking his thumb in NYPD business after spending most of his campaign demonizing the department was a mystery back then. Of course the cops were going to throw him in.

But it since has come into focus: The sad fact is this may be the dumbest administration in modern times. L’affaire Findlayter was still simmering when de Blasio made the fundamental errors that brought him to his present agony.

He disremembered that warning about tugging on Superman’s cape, picking a pair of very public fights with Gov. Andrew Cuomo — one over education policy, the other over taxes. Big mistake; the governor has been torturing him ever since.

Then de Blasio installed a cash register in City Hall and — up front and out in the open — began peddling political and policy access to big-bucks insiders. Corrupt union bosses, consultants, real estate developers and other favor-seekers lined right up — pouring in cash that was meant to finance, among other things, de Blasio’s rise to national prominence.

That didn’t happen, and now US Attorney Preet Bharara — fresh from his high-drama convictions of Shelly Silver and Dean Skelos — is sorting out what all those donors got for their money.

De Blasio made stunning — wholly avoidable — blunders, and they converged in Sunday’s petulant lawyer’s letter. In it, mayoral attorney Laurence D. Laufer took state Board of Elections counsel and long-time Cuomo hatchet-lady Risa Sugarman to task for “leaking” charges that the mayor had steered insider cash upstate in an effort to weaken Cuomo’s influence with the Senate.

Laufer says Sugarman’s playing politics, which is hilarious. Of course she is. (If she did leak the report.) Doesn’t everybody? And didn’t Mike Bloomberg once buy himself the Independence Party — lock, stock and ballot line?

But Sugarman is also a piranha — Cuomo keeps a kettle full of them — and clearly she has the attention of both Bharara and Manhattan District Attorney Cy Vance.

Thus Team de Blasio is not in a happy place.

Neither is New York City, which must be governed with wisdom and sophistication if it is to prosper — but which now finds itself led by a man who is neither wise nor sophisticated.

Indeed, he has made himself profoundly suspect — his every public move is now subject to presumptive suspicion, just as his every decision is open to wholly justified second-guessing. What’s in it for the mayor?

Sugarman’s campaign finance allegations are center-stage at the moment, but de Blasio’s breach of trust extends far beyond ill-obtained cash for upstate Democrats.

The mayor and his people siphoned off hundreds of thousands of dollars from interested parties and then seemingly proceeded without a hint of subtlety to acknowledge the dough.

Bharara, Vance, et al. need to establish specific quid pro quos in order to proceed criminally — which is only right and proper. But ordinary New Yorkers needn’t be so precise as they consider de Blasio’s fitness to serve. This isn’t a legal matter so much as it’s a moral calculation.

Is a $9 billion teachers union contract awarded only days after the union kicked $325,000 into the principal de Blasio slush fund a crime or a sin? How about a lifted nursing home deed restriction that leads to condo construction right after a $50,000 contribution engineered by a consultant who both represents the developer and is tight with de Blasio? What about those carriage horses? And so on.

Plus this, maybe the most important question of all: How did Bill de Blasio get himself so deep into the weeds so quickly?

The benign answer would be naivete. The more likely explanation is boneheaded arrogance overlaid with contempt for the rules that smarter mayors at least pretend to respect.